Composite radiopaque intracorporeal product

ABSTRACT

The invention is directed to a guidewire having a distal flexible member, such as a helical coil, which is formed with at least one highly radiopaque component and at least one high strength component. In a presently preferred embodiment, the highly radiopaque component is at least 10% and less than about 60% of the transverse cross-section of the flexible member, preferably at least 20% but less than 40%. The highly radiopaque component may be formed of radiopaque material such as platinum, gold, iridium and the like and the high strength component may be formed of a material such as tantalum, stainless steel, NiTi alloys, Co—Cr—Mo alloys and the like.

BACKGROUND OF THE INVENTION

This invention relates to the field of intracorporeal medical devicessuch as guidewires for advancing intraluminal devices including stentdelivery catheters, balloon dilatation catheters, atherectomy cathetersand other intraluminal devices within a patient's body lumen.

Conventional guidewires for angioplasty, stent delivery, atherectomy andother vascular procedures usually comprise an elongated core member withone or more tapered sections near the distal end thereof and a flexiblebody such as a helical coil or a tubular body of polymeric materialdisposed about the distal portion of the core member. The flexible bodymay extend proximally to an intermediate portion of the guidewire. Ashapable member, which may be the distal extremity of the core member ora separate shaping ribbon which is secured to the distal extremity ofthe core member extends through the flexible body and is secured to thedistal end of the flexible body by soldering, brazing or welding whichforms a rounded distal tip. Torquing means are provided on the proximalend of the core member to rotate, and thereby steer, the guidewire whileit is being advanced through a patient's vascular system.

Further details of guidewires, and devices associated therewith forvarious interventional procedures can be found in U.S. Pat. No.4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.):U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams etal.); and U.S. Pat. No. 5,345,945 (Hodgson, et al.) which are herebyincorporated herein in their entirety by reference thereto.

In a typical coronary procedure using a guidewire, a guiding catheterhaving a preformed distal tip is percutaneously introduced into apatient's peripheral artery, e.g. femoral or brachial artery, by meansof a conventional Seldinger technique and advanced and steered thereinuntil the distal tip of the guiding catheter is seated in the ostium ofa desired coronary artery.

There are two basic techniques for advancing a guidewire into thedesired location within a patient's coronary anatomy through thein-place guiding catheter. The first is a preload technique which isused primarily for over-the-wire (OTW) catheters and the second is thebare wire technique which is used primarily for rail type catheters.

With the preload technique, a guidewire is positioned within an innerlumen of an OTW device such as a dilatation catheter or stent deliverycatheter with the distal tip of the guidewire just proximal to thedistal tip of the catheter and then both are advanced through theguiding catheter to the distal end thereof. The guidewire is firstadvanced out of the distal end of the guiding catheter into thepatient's coronary vasculature until the distal end of the guidewirecrosses the arterial location where the interventional procedure is tobe performed, e.g. a lesion to be dilated or an arterial region where astent is to be deployed. The catheter, which is slidably mounted ontothe guidewire, is advanced out of the guiding catheter into thepatient's coronary anatomy over the previously introduced guidewireuntil the operative portion of the intravascular device, e.g. theballoon of a dilatation or a stent delivery catheter, is properlypositioned across the arterial location. Once the catheter is inposition with the operative means located within the desired arteriallocation, the interventional procedure is performed. The catheter canthen be removed from the patient over the guidewire. Usually, theguidewire is left in place for a period of time after the dilatation orstent delivery procedure is completed to ensure reaccess to the distalarterial location if it is necessary. For example, in the event ofarterial blockage due to dissected lining collapse, a rapid exchangetype perfusion balloon catheter such as described and claimed in U.S.Pat. No. 5,516,336 (McInnes et al), can be advanced over the in-placeguidewire so that the balloon can be inflated to open up the arterialpassageway and allow blood to perfuse through the distal section of thecatheter to a distal location until the dissection is reattached to thearterial wall by natural healing.

With the bare wire technique, the guidewire is first advanced by itselfthrough the guiding catheter until the distal tip of the guidewireextends beyond the arterial location where the procedure is to beperformed. Then a rail type catheter, such as described in U.S. Pat. No.5,061,273 (Yock) and the previously discussed McInnes et al. patent,which are incorporated herein by reference, is mounted onto the proximalportion of the guidewire which extends out of the proximal end of theguiding catheter and which is outside of the patient. The catheter isadvanced over the guidewire, while the position of the guidewire isfixed, until the operative means on the rail type catheter is disposedwithin the arterial location where the procedure is to be performed.After the procedure the intravascular device may be withdrawn from thepatient over the guidewire or the guidewire advanced further within thecoronary anatomy for an additional procedure.

An important attribute for guidewires is having sufficient radiopacityto be visualized under a fluoroscope, allowing the surgeon to advancethe guidewire to a desired intraluminal location, particularly thedistal extremity of the guidewire. Unfortunately, the most suitablematerials for guidewires, such as stainless steel and NiTi alloys,exhibit relatively low radiopacity. Accordingly, various strategies havebeen employed to overcome this deficiency. Portions of the guidewire,usually the shapeable distal tip, are typically made from or coated withhighly radiopaque metals such as platinum, iridium, gold or alloysthereof. For example, a 3 to 30 cm platinum tip coil is frequentlysoldered to the distal extremity of the guidewire. An obvious drawbackof these prior art methods is the high expense and scarcity of highlyradiopaque metals and the difficulty and expense of manufacturingproducts from these materials. The requirement of both a high degree ofradiopacity, high strength and flexibility can present design problems.

Accordingly, there remains a need for guidewires having sufficientradiopacity to allow visualization under a fluoroscope without theextensive use of expensive radiopaque metals such as platinum, gold,iridium and the like.

SUMMARY OF THE INVENTION

The present invention is directed to an intracorporeal device such as aguidewire having an elongate core member with a proximal core sectionand a distal core section and a flexible body such as a helical coilformed of metallic wire which is disposed about and secured to at leasta portion of the distal core section.

In accordance with the invention, the intracorporeal product has a bodywith multi-components, at least one highly radiopaque component and atleast one high strength component having less radiopacity than thehighly radiopaque component. The amount of the highly radiopaquecomponent and the high strength component of the flexible body dependsupon the radiopacity of each of the components. Generally, however, thehighly radiopaque component should be at least about 10% but not be morethan about 60%, preferably about 20% to about 40%, of the totaltransverse cross-section of the flexible body. The greater radiopacitythe high strength component has, lessens the amount of the expensivehighly radiopaque material which is needed.

The highly radiopaque material of the coil may be selected from thegroup of platinum, gold, iridium, highly radiopaque alloys thereof. Thepresently preferred highly radiopaque material is an alloy of 90%(wt) Pland 10%(wt.) Ir. The high strength material of the coil may be selectedfrom the groups consisting of radiopaque materials such as tantalum,tungsten and silver and non-radiopaque materials such as stainlesssteel, NiTi alloys and Co—Cr—Mo alloys. Tantalum and alloys thereof arepreferred because these materials have significant radiopacity inaddition to being high strength and can more significantly reduce theamount of expensive radiopaque material which much be used for aparticular degree of radiopacity. For example, a solid wire of 90%platinum—10% iridium will provide complete radiopacity, whereas, a wireof the same thickness with 70% tantalum core and 30% of a 90% Pt—10% Iralloy cladding will provided the same degree of radiopacity butsubstantially improved mechanical properties. The use of non-radiopaquehigh strength metals will provide a fair radiopacity with adequate orimproved mechanical properties depending upon the material used. Athickness of about 5 to about 10 micrometers of highly radiopaquematerial will usually provide complete radiopacity for intracorporealuse with conventional fluoroscopic observation.

The presently preferred form of the flexible body which is secured tothe distal core section is a two component metallic wire member such asa helical coil. Other forms include a multi-wire braid formed oftwo-component metallic wires. In one presently preferred embodiment, thetwo-component wire is made of a highly radiopaque cladding and arelatively high strength material. In this way, the radiopaque materialof the cladding can be chosen for its radiopaque properties and the corematerial can be chosen for strength properties that enhance theguidewire's performance. Alternatively, the core material may be highlyradiopaque and the cladding may be formed of the high strength material.

The distal end of the helical coil may attached directly or indirectlyto the distal end of the core member and it may also be secured to thecore member at one or more proximal locations.

In order to increase the flexibility of the distal section of theguidewire, the core member of the guidewire may be formed in aconventional manner with a distal section having at least one taperedsegment, wherein the elongate core member tapers distally to reducedtransverse dimensions. If desired, the one or more distally taperedsegments of the distal section of the elongate core member may be markedwith radiopaque markers to indicate where a tapered segment begins orends. In this way, a physician using the guidewire is able to identifythe relative flexibility and stiffness of an area of interest on theguidewire using fluoroscopic imaging.

A second or proximal coil formed of helically shaped wire may beprovided proximal to the radiopaque first coil which is formed of lessradiopaque material. The wire forming the second coil may have acircular transverse cross-section or a substantially rectangular crosssection. A coil of wire having a rectangular cross section providesincreased stiffness and coil integrity as compared to wire with a roundcross section of similar thickness, due to the increased cross sectionalarea. The proximal end of the second coil is attached to the distalsection of the elongate core member by means of adhesive, solder and thelike. The distal end of the second coil is preferably secured to thedistal section of the core member by the same mass of solder or the likethat secures the proximal end of the first, highly radiopaque coil tothe core member.

The flexible body of the present invention has at least adequateradiopacity and strength while being substantially cheaper to make thansimilar structures with helical coils formed of precious metal such asplatinum and gold. By appropriately choosing the materials, propertiescan be obtained which are better than conventional products, whilesignificantly reducing costs.

These and other advantages of the invention will become more apparentfrom the following detailed description of the invention when taken inconjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic elevational view, partially in section, of aguidewire which embodies features of the invention.

FIG. 2 is a transverse cross-sectional view of the guidewire shown inFIG. 1 taken along the lines 2—2.

FIG. 3 is an enlarged longitudinal cross-sectional view of the guidewireshown in FIG. 1 within the circle 3.

FIG. 4 is an elevational view partially in section of an alternativeguidewire wherein the distal tip of the core member is flatten andextends and is secured to the distal end of the coil.

FIG. 5 is a transverse cross-sectional view of the guidewire shown inFIG. 4 taken along the lines 5—5.

FIG. 6 is a longitudinal cross-sectional view of an alternativeguidewire design which has a proximal coil with a rectangular transversecross-section.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-3 illustrate a guidewire 10 having features of this inventionthat generally include an elongated core member 11, with a proximal coresection 12 and a distal core section 13 and a distal, highly radiopaquehelical coil 14 disposed about and secured to the distal extremity ofthe core member. A shaping ribbon 15 extends from the distal end of thecore member 11 and is secured to the mass of solder or weldment formingthe rounded distal tip 16 of the guidewire. The proximal end of theshaping ribbon 15 is secured to the distal end of the core member 11 bysuitable means such as solder, brazement, weldment or adhesive. Theproximal end of the distal highly radiopaque coil 14 is secured to thecore member 11 by mass 17 which may be solder, brazement, weldment oradhesive. A second or proximal coil 18 is secured by its distal end tothe core member by the same mass that secures the proximal end of thedistal highly radiopaque coil 14 to the core member 11. The proximal endof the proximal coil 18 is secure to the core member by solder,brazement, weldment or adhesive 20 The proximal end of the distal coil14 and the distal end of the proximal coil 18 are preferably threadedtogether at the site 17 of securing these ends to the core member 11.

The core member 11 of the guidewire 10, as shown in FIG. 1, generallymay have conventional features with conventional dimensions. Theproximal core section has a relatively constant or uniform transversecross-sectional dimensions and the distal core section 13 has a firsttaper 21, a second taper 22 and a third taper 23 which taper in thedistal direction to smaller transverse cross-sectional dimensions. Anfirst intermediate uniform dimensioned core portion 24 extends betweenthe first and second tapers 21 and 22 and a second intermediate uniformdimensioned core portion 25 extends between the second taper 22 and thethird taper 23.

As shown in more detail in FIG. 3, the distal highly radiopaque coil 14has an inner portion 26 and an exterior portion 27. The inner portion orcore 26 of coil 14 is formed of high strength metallic material such asstainless steel, NiTi alloy, Co—Cr—Mo alloys such as Elgiloy or MP35Nand tantalum (or alloys thereof). Tantalum is presently preferredbecause it also has a high degree of radiopacity in addition to highstrength. The exterior portion or cladding 27 is formed of a highlyradiopaque metallic material such as platinum, gold, iridium, palladium,tantalum, tungsten, silver and highly radiopaque alloys thereof. Ifdesired these components forming the wire of coil 14 may be reversed,i.e. the inner portion 26 may be highly radiopaque and the cladding 27may be formed of high strength material.

FIG. 4 illustrates a guidewire 30 which has various alternativeembodiments. The first alternative embodiment is the core member 31having a flattened distal extremity 32 (instead of a shaping ribbon)which extends and is secured to the rounded mass 33 of solder,brazement, weldment or adhesive which is secures the distal end of thedistal, highly radiopaque coil 34 thereto. The proximal helical coil 35may be formed of conventional stainless steel wire. As in the embodimentshown in FIGS. 1 and 3 the distal end of the second proximal coil 35 issecured to the core member 31 at the same location 36 as the proximalend of the distal, highly radiopaque coil 34. The distal, highlyradiopaque coil 34, as shown in FIG. 5 is formed of an inner component37 of highly radiopaque material and an outer component 38 of highstrength material.

Another alternative design is depicted in FIG. 6 In this design, theguidewire 40 has a core member 41 with a flattened distal extremity 42as in the embodiment shown in FIG. 4. While not shown in detail thedistal coil 43 has a highly radiopaque cladding and a high strength coreas described for the embodiment of FIGS. 1-3. However, the proximal coil44 disposed about the core member 41 has an essentially rectangularshaped transverse cross-section as compared to the circular transversecross-section of the distal coil 43. The rectangular transversecross-section provides additional support. This guidewire design isprimarily for peripheral arteries and generally has larger dimensionsthan the embodiments shown in FIGS. 1-5.

The clad wire forming the distal coil may be formed in a variety ofways. The presently preferred manner is to prepare a tubular member ofone of the components and a solid core (e.g. wire or rod) of the othercomponent suitably sized so that the tubular member formed of onecomponent can be co-drawn with the solid core of the other component toflow with the latter to form a strong bond. It is presently preferred toform the tubular member of the highly radiopaque material and the coremember of the high strength material with a lesser radiopacity. Othermeans for forming the clad wire for the distal coil include plasmaspraying one component onto a wire or rod of the other component.Physical vapor deposition may also be employed in a similar manner.Electroplating and other more conventional methods may be used to formthe clad product.

Generally, the overall length of the guidewire may range from about 80to about 320 cm, preferably about 160 to about 200 for coronary use.Typically, commercial guidewire products of the invention will come instandard lengths of 175, 190 and 300 cm. The distal section of theguidewire is about 1 to about 10 cm, preferably about 2 to about 5 cm inlength, the intermediate section is about 15 to about 50, preferablyabout 25 to about 40 cm in length. The outer diameter of the guidewiremay vary depending upon use, but typically is about 0.008 to about 0.035inch (0.2-0.9 mm). The lengths and diameters of the tapers may likewisevary The composite wire forming the proximal and distal coils willtypically have a diameter of about 0.002 to about 0.006 inch (0.051-0.15mm). A 0.002 inch diameter composite wire is typically used for forminga coil of about 0.010 to about 0.014 inch (0.25-0.36 mm) in diameter, a0.0025 inch (0.063 mm) wire for a coil with an OD of 0.0014 inch and awire of 0.0055 inch (0.14 mm) for larger OD coils. To the extent nototherwise described herein, the dimensions, constructions and materialsof the guidewire may be conventional.

Although individual features of embodiments of the invention may beshown in some of the drawings and not in others, those skilled in theart will recognize that individual features of one embodiment of theinvention can be combined with any or all the features of anotherembodiment. Various modification may be made to the invention withoutdeparting from the scope thereof.

What is claimed is:
 1. A guidewire for intraluminal advancement of a medical device within a patient, comprising: a) an elongated core member which has a proximal core section and a distal core section; and b) a flexible body which is disposed about and secured to a portion of the distal core section and which is formed of a wire having a highly radiopaque exterior formed of at least one material selected from the group consisting of platinum, palladium, iridium and alloys thereof and a high strength radiopaque interior which is made from a material selected from the group consisting of tantalum, tungsten and alloys thereof which is less radiopaque than the material of the exterior.
 2. The guidewire of claim 1 wherein the flexible body is configured as a helical coil.
 3. A guidewire for intraluminal advancement of a medical device within a patient, comprising: a) an elongated core member which has a proximal core section and a distal core section having at least one taper in the distal direction; b) a first helical coil which is disposed about and secured to a portion of the distal core section and which is formed of a wire having a highly radiopaque exterior formed of at least one material selected from the group consisting of platinum, palladium, iridium and alloys thereof and high strength interior formed of at least one material selected from the group consisting of tantalum, tungsten and alloys thereof; and c) a second helical coil which is disposed about and secured to a portion of the distal core section and which is disposed proximal to the first helical coil.
 4. The guidewire of claim 3 wherein a proximal extremity of the first helical coil and a distal extremity of the second coil are secured to the core member at a first location.
 5. The guidewire of claim 3 wherein the core member has a flattened distal tip.
 6. The guidewire of claim 5 wherein a distal end of the first helical coil is secured to the flattened distal tip of the core member.
 7. The guidewire of claim 3 wherein a flattened ribbon having proximal and distal ends is secured by its distal end to the distal end of the first helical coil.
 8. The guidewire of claim 7 wherein the flattened ribbon is secured by its proximal end to the distal end of the core member.
 9. A flexible body for an intracorporeal device comprising a helically shaped wire having a transverse cross-sectional area, a high strength interior core and a highly radiopaque exterior cladding that is at least 10% but not more than 60% of the transverse cross-sectional area of the flexible body.
 10. The flexible body of claim 9 wherein the highly radiopaque exterior cladding comprises at least 20% but not more than 40% of the transverse cross-section of the flexible body.
 11. The flexible body of claim 9 wherein the highly radiopaque exterior cladding is selected from the group consisting of platinum, iridium and alloys thereof and the high strength interior core is selected from the group consisting of tantalum, tungsten and alloys thereof.
 12. The flexible body of claim 11 wherein the highly radiopaque exterior cladding is formed of an alloy of platinum and iridium.
 13. The flexible body of claim 12 wherein the high strength interior core is formed of tantalum.
 14. The flexible body of claim 9 wherein the helically shaped wire is a codrawn member having an outer layer of highly radiopaque material and an inner core of a high strength radiopaque material which are strongly bonded together.
 15. A guidewire for intraluminal advancement of a medical device within a patient, comprising: a) an elongated core member which has a proximal core section and a distal core section; and b) a flexible body disposed about and secured to a portion of the distal core section, and which if formed of an element having a transverse cross sectional area, and which has a highly radiopaque component comprising at least 10% but not more than 60% of the transverse cross-sectional area of the flexible body and a high strength component. 